<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>组件切换一</title>
</head>
<body>
<div id="app">
    <a href="" @click.prevent="flag=true">登录</a>
    <a href="" @click.prevent="flag=false">注册</a>
    <sign v-if="flag"></sign>
    <register v-else></register>
</div>
<template id="tem1"><h2>登录组件页面</h2></template>
<template id="tem2"><h2>注册组件页面</h2></template>
</body>
</html>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    Vue.component('sign',{
        template: "#tem1"
    });
    Vue.component('register',{
        template: "#tem2"
    })
    new Vue({
        el: "#app",
        data: {
            flag: true
        }
    })
</script>